Serum factor blocking the activity of virus-induced autoreactive T lymphocytes of mice.

Normal mouse serum was found to contain a factor blocking in vivo the effect of autoreactive cells accumulating in spleens of mice infected with tick-borne encephalitis (TBE), Langat, dengue type 2 (D2), and attenuated yellow fever (17D strain) viruses. The activity of the factor was manifested only, when the autoreactive lymphocytes had H-2 antigens identical with H-2 antigens of the serum donors. The hypothesis is discussed that serum factor protects the host against clones of autoreactive T lymphocytes generated in viral infections.